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In page Cosmic inflation:

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In the early 1970s, Yakov Zeldovich noticed the flatness and horizon problems of Big Bang cosmology; before his work, cosmology was presumed to be symmetrical on purely philosophical grounds.[2] In the Soviet Union, this and other considerations led Vladimir Belinski and Isaak Khalatnikov to analyze the chaotic BKL singularity in general relativity.[citation needed] Misner's Mixmaster universe attempted to use this chaotic behavior to solve the cosmological problems, with limited success.[citation needed]